Commit 90addc6b authored Nov 21, 2017 by Huacai Chen Committed by Martin K. Petersen Nov 21, 2017

scsi: use dma_get_cache_alignment() as minimum DMA alignment



In non-coherent DMA mode, kernel uses cache flushing operations to
maintain I/O coherency, so scsi's block queue should be aligned to the
value returned by dma_get_cache_alignment().  Otherwise, If a DMA buffer
and a kernel structure share a same cache line, and if the kernel
structure has dirty data, cache_invalidate (no writeback) will cause
data corruption.

Cc: stable@vger.kernel.org
Signed-off-by: Huacai Chen <chenhc@lemote.com>
[hch: rebased and updated the comment and changelog]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

parent 860dd442

drivers/scsi/scsi_lib.c

+6 −4

Original line number	Diff line number	Diff line
		@@ -2148,11 +2148,13 @@ void __scsi_init_queue(struct Scsi_Host shost, struct request_queue q)
		q->limits.cluster = 0;

		/*
		* set a reasonable default alignment on word boundaries: the
		* host and device may alter it using
		* blk_queue_update_dma_alignment() later.
		* Set a reasonable default alignment: The larger of 32-byte (dword),
		* which is a common minimum for HBAs, and the minimum DMA alignment,
		* which is set by the platform.
		*
		* Devices that require a bigger alignment can increase it later.
		*/
		blk_queue_dma_alignment(q, 0x03);
		blk_queue_dma_alignment(q, max(4, dma_get_cache_alignment()) - 1);
		}
		EXPORT_SYMBOL_GPL(__scsi_init_queue);

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